Fixed Java language docs and added few missing features from the document.

1. Added JavaDoc comments.
2. Mentioned and used tab character by giving an example on escape character for tab.
3. Fixed the condition evaluation to true or false instead of 1 or 0.
4. Added switch case statement example for Java Strings.
5. Added default access level modifier to the Java Class.
6. Added Java Tutorial trail to links for further research.
7. Added link for OOP Concepts for Java and have put all the corresponding links as a children to this.
8. Fixed various other statements for consistency.